<!DOCTYPE html>
<html lang="zh">
<head>
    <meta charset="UTF-8">
    <title>flex深色可视化布局</title>
    <link rel="stylesheet" href="css/style.css">
</head>
<body>
<div class="main">
    <div class="top border-style"></div>
    <div class="middle ">
        <div class="left border-style">left</div>
        <div class="center">
            <div class="center-top">
                <div class="item">
                    <section class="border-style">1</section>
                    <section>2</section>
                    <section>3</section>
                </div>
                <div class="item">
                    <section>4</section>
                    <section>5</section>
                    <section>6</section>
                </div>
            </div>
            <div class="center-bottom"></div>
    </div>
</div>
</body>
</html>